FORTUNE -- In a small patch northwest of Fort Worth, Texas -- where the Barnett Shale set off the decade-long “fracking” boom that’s moved the U.S. closer to energy independence -- there’s a surprising uprising brewing over drilling for natural gas.
Energy-friendly Texas is now dealing with earthquakes.
Since Nov. 1, more than 30 small temblors have struck the rural area around Azle (pop. 11,000), and many residents are blaming the quakes on underground disposal wells, used to get rid of wastewater generated during the fracking and production process. Drillers inject the salty wastewater into wells a mile or two deep.
The quakes have already triggered a raucous town hall meeting, a decision to hire Texas’s first-ever state seismologist, and a pledge to study the problem. Unsatisfied with this response, a busload of residents, demanding that the disposal wells be shut down immediately, appeared on Tuesday in Austin at a meeting of the Texas Railroad Commission, the state’s industry-friendly oil-and-gas regulator. According to an account by a Fort Worth Star-Telegram reporter, one protester pulled out a guitar during the meeting and broke into a rendition of Elvis Presley’s “All Shook Up.”
The big question: Are the disposal wells causing the earthquakes?
Alan Brundrett, an insurance agent who serves as Azle’s part-time mayor, has no doubt. Brundrett recalls the first earthquake he experienced, during a city council meeting in November. “It felt like someone kicked the back of your chair. It was strange.” He felt another shortly after midnight in December, as he was lying in a recliner in his three-bedroom home, watching a horror flick. “It sounded like something exploded outside,” says Brundrett. “The whole house shook, and the windows rattled. I jumped about two feet out of my chair.”
In tiny Reno, a few miles to the north -- near the site of active disposal wells and the suspected epicenter of the shaking -- cracks have appeared in the walls and floor of the city council chamber. Some area residents blame the quakes for sinkholes on their property and stuck doors and windows in their homes. Now Brundrett says, “everybody I know has an earthquake app loaded on his cellphone.” (QuakeFeed is a favorite.)
The tremors have ranged from 2.0 to 3.6 on the Richter scale, with nine measuring 3.0 or higher, according to U.S. Geological Survey geophysicist Dr. William Ellsworth. While frightening and felt by thousands of residents, none of the quakes so far has caused injuries or major damage.
Hydraulic fracturing (which breaks apart shale rock to extract oil and gas) has been blamed for various ills, including contamination of water wells. Yet geologists say it’s not the fracking, but rather disposal wells -- which inject millions of gallons of water deep underground -- that pose the greater risk of meaningful earthquakes.
Ellsworth, who is helping coordinate efforts to zero in on the pattern (including the installation of seismographs in the region), says few injection wells cause earthquakes, but there is strong evidence that a handful of them -- perhaps located near an existing fault -- do. In Texas, says Ellsworth, “everything is happening in a very limited area. We don’t know that there’s a connection at this point. There’s a correlation, but correlation is not causation. People need to keep that in mind.”
In a recent update to an article Ellsworth published last July in Science (paywall), he and two colleagues noted that that the rate of quakes (3.0 and larger) in the central and eastern U.S. has multiplied to about a hundred a year during 2010-2013, coinciding with the increase in fracking, which requires disposal wells. This compares with an average of 20 quakes a year from 1970-2000.
In closely studied cases where disposal wells are the suspected culprit, a shutdown of the well -- or even a reduction in the rate of water being injected underground -- has ended the earthquakes.
After the string of tremors around Azle hit double figures -- “Another day, another earthquake in North Texas,” read one recent Star-Telegram headline -- Brundrett persuaded the Railroad Commission to convene a town hall meeting at the local high school on Jan. 2. About 900 angry residents showed up, calling for the injection wells to be shut down immediately.
They booed and hooted as Commissioner David Porter refused to respond to questions, insisting that he was there only to listen. “That pissed off everybody from the beginning,” says Brundrett.
The Texas commission has long viewed its relationship with the energy industry as equal parts promoter and regulator. Commissioners regularly win election with heavy financial support from oil and gas interests. Porter’s official biography describes him as a CPA who built a successful practice in Midland, “providing accounting and tax services to oil and gas producers, royalty owners, oil field service companies, and other small businesses and individuals.”
“The Railroad Commission is concerned and involved, but we have to base our actions on sound science and proven facts, not speculation that appears in some newspaper articles and some blogs,” he told the crowd in an opening statement.
After two hours, local media reported, Porter ended the meeting, then bolted out the back door, escorted by state troopers. Afterward, the Railroad Commission announced it would be seeking more data on the problem and hire an in-house earthquake expert. (Porter’s staff said he would have no further comment.)
Those unwilling to wait rode down to Austin on Tuesday to demand immediate action.
Brundrett declined to join the bus trip. He believes the quakes show a clear pattern, but acknowledges the need for additional study.
“I’m pro oil and gas,” he says. “When people turn their light switch on, they want their lights to come on. The energy has to come from somewhere. It’s just sometimes being done in a bad way or in the wrong place.” Like many residents in the Barnett Shale region, Brundrett has received income from leasing land to drilling companies.
He doesn’t blame the drillers for demanding more proof. “It’s common sense that everyone wants the scientific evidence. They don’t want to get into the position of having to shut down everything any time everybody cries wolf.”
But when it arrives -- within a month or two, Brundrett expects -- he says the disposal-well operators will need to respond quickly. “If we get the data, and it does indeed link the injection wells to earthquakes, and they fail to do anything, then it’s time to get out the pitchforks and torches.”